I can second Ralf’s recommendation for considering Andy Chiavetta at Aerochia if you are in need of a plenum for a Legacy or a Lancair IV.

http://aerochia.com/kits_ES_speedmod.html

That link will take you to the page for the IV.

Lynn Farnsworth

Hi Bob,

I built a plenum for my TSIO550. Unfortunately I don’t have before/after data on it but Charlie Kohler told me that my heads are running very very cool even having the tight lower old cowl that became obsolete because of cooling issues. My oil temp is running a little above average (approx 190F at an OAT 20…25F at FL200)

The actual plenum was a piece of cake – I just taped down cardboard sheets on the engine, waxed it and laid 3 layers of carbon on top. After it was dry I removed it and cut it to size.

Making the baffling and modifying the cowl to reduce the leaks turned into a real project. Fred Moreno has a lot of helpful tips in the archive for the baffling. I also copied the design of the sliding oil door from Brent Regan. The air-inlet is copied from 320/360 pictures ( when it comes to plenums there is a lot more know how than on the IV side – obviously the 320/360 group is more fanatic about speed J)

I don’t remember how many hundred hours I have in this – but it was a lot. You need a lot of passion to go there especially since you have a flying airplane already.

If you look for the most economical and quick solution I probably would go to Aerochia – I think they have a complete cowl-plenum- design that they sell.

If you really want to do this by yourself you are welcome to stop at 5G7 any time and look at my design to collect further ideas.

Ralf

Gents - a couple of questions regarding plenum design (IV-P/TSIO 550 specific)